Haem-rotational disorder in monomeric allosteric cyano-Met insect haemoglobins monitored by resonance Raman spectroscopy.
Haem-rotational disorder in monomeric allosteric cyano-Met insect haemoglobins monitored by resonance Raman spectroscopy.
复制标题
通过共振拉曼光谱监测单体变构氰基-Met昆虫血红蛋白的血红素旋转紊乱。
DOI：
10.1016/0022-2836(87)90680-2
复制
发表时间：
1987
影响因子：
5.6
通讯作者：
Parish,DW
中科院分区：
文献类型：
--
作者：
Gersonde,K;Yu,NT;Kerr,EA;Smith,KM;Parish,DW
用共振拉曼光谱研究了单体变构昆虫血红蛋白CTT III和CTT IV的氰基-Met形式的血红素旋转紊乱（血红素插入到围绕α，γ-中轴旋转180 °的珠蛋白中）。最重要的是，在不存在重叠乙烯基振动的情况下，我们确定了57 Fe氘代-IX CTT IV与13 C15 N-连接时在401 cm− 1和422 cm −1（pH 9.5）处的两个Fesingle键C单键N弯曲振动，这归因于两个血旋分量。一个Fesingle键G单键N弯曲模式在422 cm − 1处显示了pH诱导的位移到424 cm−1（pH 5.5），表明t → r构象转变，而另一个弯曲模式是pH不敏感的，代表非变构组分。然后，观察到Fesingle键N（His）（在313 cm−1处）和Fe-CN（在453 cm−1处）伸缩模的锐化，并出现一个Fesingle键C单键N弯曲模（在412 cm−1处）。在cyano-Met proto-IX CTT III中，由乙烯基的氘代反应指定的两个乙烯基弯曲振动（在412 cm− 1和591 cm− 1处）也反映了血红素无序。412 cm− 1的乙烯基振动是通过与Fesingle键C单键N弯曲模式之一（在412 cm−1处）的空间耦合而强度增强的。在cyano-Met形式的proto-III CTT III中，这种乙烯基振动被转移到430 cm− 1，导致强度急剧下降。这是最有可能的是，特定的乙烯基-蛋白质相互作用的位置4在一个血液旋转组件是Fesingle bondCsingle bondN和乙烯基弯曲模式之间的耦合的起源。通过~（54）Fe ~（57）Fe和~（13）C ~（15）N/~（12）C ~（15）N/~（13）C ~（14）N/~（12）C ~（14）N同位素交换，确定了Fe-N的伸缩振动和Fe-C-N的弯曲振动。
The haem-rotational disorder (insertion of haem into globin rotated about the α, γ-meso axis by 180 °) has been investigated in the cyano-Met form of the monomeric allosteric insect haemoglobins, CTT III and CTT IV, by resonance Raman spectroscopy. The effect of haem disorder on the resonance Raman spectra has been observed in proto-IX, deutero-IX, and meso-IX CTTs.Most importantly, in the absence of overlapping vinyl vibrations, we have identified two Fesingle bondCsingle bondN bending vibrations at 401 cm−1and 422cm−1(pH 9.5) for57Fe deutero-IX CTT IV ligated with13C15N−, which are attributed to the two haem-rotational components. One Fesingle bondGsingle bondN bending mode at 422cm−1shows a pH-induced shift to 424 cm−1(pH 5.5) indicating thet→rconformational transition, whereas the other bending mode is pH-insensitive, representing a non-allosteric component.By replacing the unsymmetrical porphyrins with the “symmetrical” protoporphyrin-III we eliminate the haem disorder. Then, sharpening of the Fesingle bondNɛ(His) (at 313 cm−1) and Fe-CN (at 453 cm−1) stretching modes is observed and a single Fesingle bondCsingle bondN bending mode (at 412 cm−1) appears.In cyano-Met proto-IX CTT III two vinyl bending vibrations at 412 cm−1and 591 cm−1assigned by deuteration of the vinyl groups also reflect the haem disorder. The 412 cm−1vinyl vibration is intensity-enhancedviathrough-space coupling with one of the Fesingle bondCsingle bondN bending modes (at 412 cm−1). In the cyano-Met form of proto-III CTT III this vinyl vibration is shifted to 430 cm−1resulting in a dramatic drop in intensity. It is most likely that the specific vinyl-protein interaction at position 4 in one of the haem-rotational components is the origin of the coupling between the Fesingle bondCsingle bondN and vinyl bending modes. The Fe-Nɛ(proximal His) and the Fe-CN stretching vibrations as well as the Fe-C-N bending vibration have been identified by54Fe57Fe and13C15N/12C15N/13C14N/12C14N isotope exchange.